Helical inverse free electron laser accelerator for efficient production of high quality electron beams.

Recently the UCLA BNL helical IFEL experiment at the Accelerator Test Facility (ATF) showed for the first time capture and high gradient acceleration of monoenergetic electron beams from a helical inverse free electron laser. Using a modest intensity ~1013 W/cm2 laser--several orders of magnitude less than those used in laser wake-field accelerators--and a strongly tapered 0.5 m long helical undulator, we demonstrated energy doubling of a 52 MeV electron beam with >100 MV/m average accelerating gradient and excellent output beam quality. In order to improve the fraction of electrons captured, a prebuncher module is being prepared for testing next month. Simulations show that 70 to 90% of the beam should be accelerated to a final energy of 97 MeV with 2% energy spread. The high efficiency acceleration will enable the first IFEL driven inverse Compton scattering experiment. [ABSTRACT FROM AUTHOR]